The present invention relates to determining positions of intra-patient probes. In particular, the position of an intra-patient probe, such as a catheter, is determined relative to another catheter or tissue for imaging.
Successful intra-cardiac or surgical procedures require accurate information about the spatial position of the surgical or other devices with respect to anatomy. For example, during radiofrequency ablation procedures, knowing the position of the ablation device is important. Radiofrequency electrical ablation is performed on the conduction pathways adjacent to the pulmonary artery. The ablation is performed inside the ventricle as high up on the conduction pathway as possible while avoiding ablating the inside of the pulmonary artery.
Accurate placement of the ablation catheter for performing the ablation may be obtained using visualization. Fluoroscopy can be used to visualize a projection siluette of a catheter and anatomy. The dimensions and distances along the projection direction cannot be seen using fluoroscopy. Minimized exposure to X-rays performed during fluoroscopy imaging may also be desired.
U.S. pat. No. 6,490,474 avoids the use of X-ray radiation to determine the position of catheters. The relative position of multiple catheters is visualized using ultrasound transducers. The transducers are spaced along each of two or more catheters. Ultrasonic time-of-flight is used to identify the relative spatial locations of the transducers. The relative transducer locations, the known mechanical properties of the catheters and the positioning along the catheters allow the relative trajectories of the catheter bodies to be predicted. However, identifying the relative position of two or more catheters does not in itself visualize the anatomy and, even if one of the catheters is a catheter probe for imaging, the method may not provide sufficient information.